A top officer in Britain's Royal Air Force (RAF) has warned that its ability to carry out future missions is under threat if Britain's involvement in Libya extends past the summer, a report said Tuesday.

The comments by Air Chief Marshal Simon Bryant, the deputy head of the RAF, come just days after the navy chief warned of tough choices if the Libyan campaign lasts more than six months.

In a briefing paper for lawmakers obtained by the Daily Telegraph newspaper, Bryant, the air force's head of combat operations, said missions in Afghanistan and Libya were together placing a "huge" demand on resources.

Bryant described morale as "fragile", with many areas "running hot" as defence cuts brought in by Prime Minister David Cameron's year-old coalition government take effect.

"Two concurrent operations are placing a huge demand on equipment and personnel... Should Operation Ellamy (Libya) endure past defence planning assumptions the future contingent capability is likely to be eroded," Bryant said.

A week ago First Sea Lord Admiral Mark Stanhope, the head of the Royal Navy, issued a similar warning and added that the Libya campaign would have been cheaper and "more reactive" had Britain not scrapped its last aircraft carrier.

"If we do it longer than six months we will have to reprioritise forces. That is being addressed now," Stanhope said in a military briefing. "It could be from around home waters. I will not prejudge what that decision will be."

Cameron scrambled to limit the damage after Stanhope's comments, holding a meeting with the navy chief and insisting Britain could sustain its Libya operation long-term.

Britain has been one of the chief players in the NATO military alliance implementing a United Nations mandate to enforce a no-fly zone and protect civilians in Libya as leader Moamer Kadhafi attempts to crush a rebel uprising.